1. Field of the Invention
The present invention relates to a fuel injection valve of an internal combustion engine.
2. Description of the Related Art
In a fuel injection valve used conventionally, a needle valve is attracted by an electromagnetic force generated by a solenoid to open the valve and is urged by a spring to close the valve. When the valve is opened or closed, the needle valve collides with a member for cooperating to define an opened or closed position thereof and then may bounce. As the needle valve bounces at its opened or closed position, a secondary injection takes place to thereby deteriorate the linearity of the fuel measuring.
To solve this problem, Japanese Patent Examined Publication No. 58-54266 has proposed a counter technique. In this technique, a bounce in the valve opening is controlled by adding a pressure higher than fuel pressure to the back of a needle valve. On the other hand, in Japanese Patent Unexamined Publication No. 53-59131, a weight is provided in an upper portion of a needle valve so as to reduce the valve opening speed, thereby restraining a bounce in the valve opening.
In a fuel injection valve disclosed in Japanese Patent Examined Publication No. 58-54266, since a control portion for back pressure becomes large-scale and complicated, the apparatus itself is enlarged. Further, since a back pressure is applied to the needle valve, an excessive impact force is applied to a seat portion of the valve, resulting in a possibility that the durability of the seat portion is deteriorated. On the other hand, in a fuel injection valve disclosed in Japanese Patent Unexamined Publication No. 53-59131 as well, provision of a weight member brings about enlargement of the apparatus. Further, when the needle valve is seated, an additional impact force corresponding to the weight member is applied simultaneously, and therefore, there is caused a possibility that the strength and hence the durability of the seat portion is also deteriorated.